132 PA THOGENIC BACTERIA . 



illation of the serum containing them, are not injured by 

 light, do not undergo any rapid spontaneous alteration 

 when kept, sometimes not losing very much of their 

 activity in a year or more. They are not destroyed by 

 carbolic acid, trikresol, chloroform, formaldehyd, cam- 

 phor, or other substances recommended for the preserva- 

 tion of the serums. When the albumins are removed from 

 the serums they lose most of the antitoxic strength, which 

 seems to be thrown down with the albumins. Most of the 

 virtue of the serum is precipitated with the globulins. 

 All attempts to extract the antitoxin in a pure form 

 have failed, the nearest approach to success having prob- 

 ably resulted from the experiments of Brieger and Boer, 1 

 who separated it as salts of heavy metals, especially zinc. 



Being in all probability of proteid nature, the anti- 

 toxins are all destroyed in the alimentary canal. In the 

 researches of Carriere 2 the destruction was found to 

 depend chiefly upon the pancreatic secretions, though in 

 part upon the activity of intestinal juices, the contained 

 bacteria, and the lining epithelium. 



Action of Antitoxin upon Bacteria. — Except when the 

 immunization of the animal furnishing the protective 

 serum is accomplished by the employment of living 

 cultures or germ-containing cultures so as to be pos- 

 sessed of the additional phenomenon of bacteriolysis, it 

 cannot be said that the antitoxin has any direct action 

 upon the bacteria. It is, indeed, said by Martini that 

 the diphtheria bacillus, which usually grows well upon 

 blood serum, will not grow upon antitoxic serum. This 

 observation, however, lacks confirmation. 



Action of Antitoxin upon the Toxin. — This may be 

 either a form of direct chemic action or an indirect 

 action produced either by stimulation of the cells of the 

 body or by bringing about combination between the 

 toxin and certain substances in the blood or tissues. 



i. Theory of Chemic Action. — This is the original 



1 Zeitschrift fiir Hygiene, 1896, Bd. xxi., p. 259. 



2 Ann. de I , Inst. Pasteur, May 25, 1899, xiii. 



